From Kate Golden at Wisconsin Watch, the Wisconsin Center for Investigative Journalism, we learn that milk cows in Wisconsin are producing 3 times as much milk per cow as they did in 1924. As interesting as the data itself is the very nice use of formatting and dual axes to tell the story:

Earlier, Kate had written to the Tableau Public team: "WCIJ is one of the many new experiments in modern journalism. We collaborate with other news outlets (e.g., the Center for Public Integrity, Wisconsin Public Broadcasting) so we can combine our reporting and distribution power -- and our M.O. is to give away our stories for free, mostly to the sorts of small news outlets that can't afford to do investigative reporting. We're based on donations and grants, with a budget this year of about $240k this year."

We're all for creative experiments in journalism that help support investigative reporting. Our M.O. is to provide Tableau Public to bloggers and journalists to support that.

Note: Mark Perry did a great riff on this viz by combining it with some milk price data. You can see the viz on his blog, Carpe Diem.


I believe that dual axis charts are rarely the most effective quantitative analysis approach.

In this case the author has charted the actual numbers, but key points describe the percent difference.

Here is a chart of the percent difference from first, the key notes instead of the actual values:

Now you can visually see, 35% less Cows, 150% more Milk, because Production per Cow is up 280% from 1924 to 2009.

I added a slider so you can change your point of reference.

Additionally, here is a scatter line of the data that highlights a possible pattern:

Considering only these three values, I could see that if the production per cow continues moving upward, we will again see a decline in the number of milk cows.

joemako---both of your graphs, especially your % difference graph, are a more insightful spin on the dual axes variety! Thanks for sharing.

Would love to see this over-layed with a sales trend for synthetic bovine hormones.

Nice easy graph. I normally prefer to
split historic from recent data. Recent data
is not more than 10years old. Beyond it gets
history for historians.
So what about the last 10years?
What would actually worry me is that
milk production still growth and cows still decrease.
For that, I would have created 2 calculated fields:
Delta Prod and Delta Cow, the difference between
2 consecutive years for each series.

What this data means to me: This is why I drink organic milk from regular cows.

Everyone can benefit from milk. Milk has been a good nutritional source. It has the ability to prevent person from diseases, it also makes our teeth and bones strong and also it aids you in sleeping because of the balanced nutrients milk provides our body. I've read this site were I get many facts about benefits of milk in our body.

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